Chreeyiss

I believe a PDS watch is issued for 80% and up, but I’m guessing they didn’t go that high because of the potential for these storms to merge upscale somewhat quickly. I bet they’d have gone PDS if it looked like this were going to stay discrete for longer.

I would guess it gives the wrong idea to the public. The subset of people who actually recognize the difference between a svr watch and a tor watch, but aren’t invested enough to frequently check in are probably inclined to view it as a “cry wolf” incident if a tornado watch is issued for a risk that’s so low that only 1 or 2 tornadoes occurs in an entire watch box. Most people in this group are only aware of what’s happening in their city or news coverage that cuts into their tv shows.

Not that it really matters this far out, but despite the relative consistency in the gfs (cmc and euro have been all over the place), I see some things that are far from being nailed down: - Timing: looks like overnight Tue-Wed (though gfs tends to be too progressive, might this eventually turn into a Wed event for the plains?) - 500mb pattern: Will there be a northern lobe and associated surface low in Kansas and Nebraska, as shown on some runs, or will the southern lobe in NW Texas remain dominant? - Will the low level jet sync sufficiently with the upper levels and create a favorable shear profile, and if so, where? (imagine this is a function of the 2 points above) First thing that comes to mind for me looking over these runs, at least for Texas and Oklahoma, is an overnight MCS. If shear and instability are sufficient, maybe there would be an embedded supercell/tornado risk. 0z GFS run doesnt really maximize either of these though. Of course, all of this is speculation on my part for entertainment purposes and an attempt to see if I've learned anything at all over time regarding pattern recognition. It also makes the lofty assumption that the GFS is onto something to begin with. Guess we'll see.

I’m not broad brushing that as rule in general, but for this particular setup, from what I’ve seen on the models, the cap looks like it prevents surface based instability from being fully utilized unless temps exceed about 66 degrees. I might be wrong, but it looks like that’s the main differentiator between central Texas and points further north in DFW where the shear profiles are at least as extreme. If I’m wrong on this though, I would love to learn more.

Looks like Tuesday has taken the title of biggest day instead of Monday, but Monday has very high potential too. The SRH values in north and central Texas Monday afternoon are absurd. Like 500-750m2/s2. However, if temps stay mid 60s or below during the afternoon across this area, the full potential probably won’t be realized

Agreed, there doesn't seem to be as much of an overlap between that extremely favorable shear and sufficient instability on these more recent runs. Looks more like a broad brushed slight with a pocket of enhanced in central Texas to me, if these trends hold.

True, I guess we will see. The shear profiles look very favorable across the eastern half of Texas, and the SPC notes this in their convective outlook as well. GFS does sometimes underestimate instability and lapse rates on these early season events, but I wouldn't be surprised the event busts up here for the reason you mentioned. CLL and south may end up being the bullseye where thermos are better.

Won’t sleep on tomorrow, but Monday is continuing to look like the main event.

Today has met my expectations here in Dallas proper. It’s hailed 3 times here in the last hour, though fairly small. Got some good bursts of rain and a couple nice SLCs to look at. Maybe more on the way judging by radar, though I imagine these latest storms have probably tapped most of the good conditions over me.

Unless you live along or west of 35, you might luck out. Lots of storms firing in the metro now

First attempts at initiation look to be appearing south of Arlington

True the HRRR is back east, but its soundings show >1500j/kg in an uncapped atmosphere along and east of 35 by 5pm. Not going to take much to get storms to initiate west of where it currently depicts. NAM, ARW, and ARW2 are closer to 35 with initiation.

I’ve seen wxtwitter abuzz with comments along the lines of “who cares what EF rating the tornado gets when there are lives lost and damage done?” I understand that thought, as there are a lot of people who seem to care only about the damage rating, but the two sentiments aren’t mutually exclusive, as many others have pointed out. What you posted above is why we should still care about the integrity of the EF rating. Quick googling shows that there have been 631 F/EF 4+’s documented from 1950 to 2017. With an average of 1200 tornadoes per year, and an ef4+ rate of 20% according to the study, that means if we could derive tornado intensity from measures other than just damage, it would only take about 3 years to document the same number of ef4+ tornadoes that we have accumulated over the span of 67 years. Findings like this demonstrate the impacts of the limitations of the EF scale, and the truncation of a given tornado sample size to less than 5% of what it should be must have some pretty significant impacts on the ability to derive trends and make predictions.

Obviously you’re the met, so your opinion is much better informed than mine, but it seems to me that if if our intensity scale is to continue relying heavily on damage produced over other indicators, that the scale needs to be updated with more non-urban damage indicators for EF4+ tornadoes, rather than a downward adjustment of winds in the ef5 category. In concept, it doesn’t make a whole lot of sense that a tornado’s intensity is only as strong as the building it hits (or doesn’t hit) but even with improvements in technology, it’s still the best we’ve got. Tornadoes predominantly hit rural or even unpopulated areas, and if tornado intensity is going to continue to be evaluated by this methodology, I would think the next logical step in improving the scale would be to accommodate that fact better. The NIST slideshow about Joplin that was posted above makes note of the large amount of subjectivity that comes into play when evaluating unconventional damage indicators due to construction methods that can’t generate an ef5 rating. I’m sure Tim’s statement was made on the fly, but using two tornadoes that were clearly well above the F5 threshold as the benchmark for 201mph winds doesn’t seem like a fair comparison to me. If I had any say in the matter, I personally would only advocate for lowering the wind threshold if structural engineering studies determined that what is generally considered ef5 damage was produced at lower wind speeds, or if we were to lower the standard for what is considered ef5 damage. Let me know if my line of thinking here isn’t correct.

Like many of you, I am confused by Tim’s statement. Our benchmark for ef5 now is one tornado measured at over 300mph, and another tornado that imparted f5 impacts on a given location for longer than practically any other on record? If that’s the case, why would we even consider 201 mph the threshold, and not something higher like 250 or 300? edit:typo